Field of the Invention
The present invention relates to systems and methods for forming pulse signals by operation of switch mechanisms causing impedance variations in a circuit containing a transformer.
In accordance with a first embodiment of the invention a method and a system are provided for communicating from the secondary side of an isolation transformer to a processor via operation of a circuit containing an appropriate switch mechanism providing impedance variations forming pulsed voltage signals which are transmitted through the primary of said transformer onto a power transmission line or cable.
According to a further embodiment of the invention a monitoring system is provided for airfield lighting lamps powered in series from an ac current supply via a transmission or supply cable. In the system, each of the lamps is associated with an isolation transformer having a secondary side containing the lamp, each lamp having assigned thereto a unique address and an associated lamp monitoring unit which is able to communicate with a communicating unit by means of a communicating signal transmitted over said transmission cable.